我终于找到了解决办法：
https://techotom.wordpress.com/2014/11/12/mocking-remoteaddr-with-spring-mvc/
基本上用这个方法我们可以改变请求的每个参数。
因此，首先我们必须定义更改请求内容的方法：

private static RequestPostProcessor remoteHost(final String remoteHost){
    return request -> {
        request.setRemoteAddr(remoteHost);
        return request;
    };

而不是用方法 with(...) 在 MockHttpServletRequestBuilder 对象我们必须注入这个方法的结果。

MockHttpServletRequestBuilder requestBuilder = get("/user/prop").
         .with(remoteHost("mockhostdomain.com"));

使用mockmvc，您可以执行以下操作：

Map<String, String> req = new HashMap<>();
//        req.put("")
        ObjectMapper mapper = new ObjectMapper();
        ObjectWriter ow = mapper.writer().withDefaultPrettyPrinter();
        java.lang.String requestJson = ow.writeValueAsString(req);

        String responseString = this.mockMvc.perform(post
                ("/authorization/activated")
                .with(request->{request.setRemoteAddr("192.168.0.2");return request;})
                .contentType(MediaType.APPLICATION_JSON)
                .content(requestJson)
                .header("Authorization", bear)
        .header("X-Device-Id","7fb0c4e49aec4c5a9a089d0c84f7078b"))
                .andReturn().getResponse().getContentAsString();
        System.out.println("[POST result]:" + responseString);